How can you sleep if you’re surrounded by predators that might eat you as soon as you nod? I’m sleeping.
Northern elephant seals spend part of each year on the beach during the mating season. During that time, I can sleep up to 10 hours a day.
That said, they also spend up to eight months searching for prey at sea, never coming ashore for the entire time. , wondering how they avoid predators such as sharks and killer whales while sleeping.
To find out, researchers at the University of California, Santa Cruz set out to remotely monitor the brain waves of captive female elephant seal juveniles on the beach of Año Nuevo State Park, California.
Before being released into the southern tip of Monterey Bay, EEG (electroencephalogram) electrodes were attached to the outside of each animal’s head to monitor brain activity. The electrodes were connected to a small data logger and covered with a protective neoprene cap. All hardware, including the time depth recorder and accelerometer, are designed to be discreet.
After the seals were released, they swam through the deep underwater Monterey Canyon back to Año Nuevo. Diving behavior during this period was reported to be very similar to behavior during months-long foraging trips. Upon reaching the destination shore, all of the seal’s head covering was removed by scientists.
Based on data recorded from 13 seals and previously recorded dive depth data during foraging trips of 334 adult seals, we found that the animals typically only slept about 2 hours every 24 hours. It turns out. They do so for about 10 minutes at a time during deep ‘drift dives’ that take place throughout the day.
Jessica Kendall Burr
Seals slowly whirl downward as they sleep, sometimes actually lying on the ocean floor, reaching depths rarely ventured by predators. , occurs when elephant seals are awake and breathing at the surface.
“Elephant seals are unusual in that they sleep more than 10 hours a day on land and less than two hours a day at sea.” “They can hold their breath for long periods of time, so they can go into deep sleep on these dives at safe depths below the surface.”
A paper on this study was recently published in the journal chemistry.
Source: University of California, Santa Cruz, American Association for the Advancement of Science (via EurekAlert)
